1. Field of the Invention
This invention relates to a hot stamping method. Indication panels manufactured by this hot stamping method are applied in various measuring instruments for cars, aircraft and other vehicles.
2. Description of the Prior Art
In Japanese Examined Patent Publication No. 56-9708 (published in 1981) the present applicant proposed a hot stamping method.
According to the conventional hot stamping method, some characters, patterns and the like are, as shown in FIG. 6A, printed by an adhesive 2 of acrylic resin or the like upon a substrate 1 such as paper, leather, metal plastic material, etc., and a foil sheet 3 is placed on the printed surface. Such foil sheet 3 is heated by a silicone rubber 5 attached to the bottom of a heating plate 4 and then pressed on the substrate 1. That is, as shown in FIG. 6B, a foil B is transferred to a portion of the adhesive 2.
According to an example of the foil sheet 3, the foil B is adhered to a base film A by way of a release agent H. The purpose of release agent H is to release the base film A easily from the foil B. As shown in FIG. 6C, the foil B comprises a foil body a, a coating layer b and a lacquer layer c disposed facing the inner surface of the base film A to protect the foil body a. The coating layer b may have adhesion to e.g. a metal plate, a plastic plate, a glass plate and the like respectively. However, there is the case that it has no adhesion to some kinds of plates.
According to this conventional technique, the coating layer 6 is not adhesive to the base plate. More specifically, it has no adhesion thereto under an application of heating and pressure.
Accordingly, the foil sheet 3 heated and pressed by the silicone rubber 5 is adhered to the adhesive 2 on the substrate 1, but it is not adhered to any non-adhesive portion of the substrate 1, because the coating layer b is non-adhesive. Therefore, when releasing the base film A from the foil B, the foil B remains on the adhesive 2 portion, namely the former is transferred to the latter.
According to this conventional hot stamping method, the characters, numerals, patterns, etc. are printed by the adhesive 2, to which the foil B is transferred. Accordingly, an expensive relief printing is not necessary.
However, when leaving the characters, numerals and patterns as they expose natural surfaces of the substrate 1 and transferring the foil to the other part of the substrate 1, the printing (or transferred) area of the adhesive becomes thicker and its consumption is increased. Consequently, such a conventional hot stamping method becomes disadvantageous.
Accordingly, this conventional hot stamping is not applicable for an example in FIG. 5, in which the characters/numerals 6 and the graduations 7 having a small and narrow area remain on the surface of a plastic plate 8 while exposing natural surfaces thereof and the foil sheet 3 is transferred to a wider portion of the plastic plate 8.
Under such circumstances, when applying the printed adhesive 2 to the foil sheet 3 under the application of heating and pressure, the disadvantage is that the adhesive 2 may enter a recessed portion 6 (or recessed characters or the like) as shown in FIG. 8.
Still further, when pressing the foil sheet 3 on the adhesive 2 by means of the silicone rubber 5 or the like, the shoulder 2a of the adhesive 2 is deformed as shown in FIG. 8. In addition, since the solidified adhesive 2 is fused during the heating and pressing process, it is deformed, although its thickness is about 10.mu.. Thus, the edges of the recessed characters/numerals 6 are collapsed, so that it is impossible to obtain clear profiles of the recessed characters/numerals.